Inorganic hollow yarns and method of manufacturing the same

ABSTRACT

Disclosed herein is a method of manufacturing inorganic hollow yarns, such as cermets, oxide-non oxide composites, poorly sinterable non-oxides, and the like, at low costs. The method includes preparing a composition comprising a self-propagating high temperature reactant, a polymer and a dispersant, wet-spinning the composition through a spinneret to form wet-spun yarns, washing and drying the wet-spun yarns to form polymer-self propagating high temperature reactant hollow yarns, and heat-treating the polymer-self propagating high temperature reactant hollow yarns to remove a polymeric component from the polymer-self propagating high temperature reactant hollow yarns while inducing self-propagating high temperature reaction of the self-propagating high temperature reactant to form inorganic hollow yarns. The composition comprises 45˜60 wt % of the self-propagating high temperature reactant, 6˜17 wt % of the polymer, 0.1˜4 wt % of the dispersant, and the balance of an organic solvent.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of Korean PatentApplication No. 10-2009-0135865 filed on Dec. 31, 2009, the contents andteachings of which are hereby incorporated by reference in theirentirety.

BACKGROUND

1. Field

The present invention relates to inorganic hollow fibers or yarns.

2. Description of the Related Art

Inorganic hollow yarns have a hollow center and are widely used due tomerits, such as a very high membrane area per volume, good productivity,and the like. Thus, when inorganic membranes are produced using theinorganic hollow yarns, the membranes may be applied to processes suchas water treatment, gas separation, liquid separation, dust filtration,membrane reaction, catalyst carriers, air conditioning, and the like.

SUMMARY

One aspect of the present invention is to provide a composition forinorganic hollow yarns, which may be used to produce cermet hollow yarns(ceramic-metal composite hollow yarns,) oxide-non oxide composite hollowyarns, and poorly sinterable non-oxide hollow yarns.

Another aspect of the present invention is to provide a method ofmanufacturing inorganic hollow yarns using the composition throughself-propagating high temperature reaction.

In accordance with one aspect of the invention, a composition forinorganic hollow yarns includes 45˜60% by weight (wt %) of aself-propagating high temperature reactant, 6˜17 wt % of a polymer,0.1˜4 wt % of a dispersant, and the balance of an organic solvent.

The self-propagating high temperature reactant may be a material capableof forming one of a ceramic-metal composite, an oxide-non oxidecomposite, and a poorly sinterable non-oxide composite.

In accordance with another aspect of the invention, a method ofmanufacturing inorganic hollow yarns includes: preparing a compositioncomprising a self-propagating high temperature reactant, a polymer, anda dispersant; wet-spinning the composition through a spinneret to formwet-spun yarns; washing and drying the wet-spun yarns to formpolymer-self propagating high temperature reactant hollow yarns; andheat-treating the polymer-self propagating high temperature reactanthollow yarns to remove a polymeric component from the polymer-selfpropagating high temperature reactant hollow yarns while inducingself-propagating high temperature reaction of the self-propagating hightemperature reactant to form inorganic hollow yarns.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart of a method of manufacturing inorganic hollowyarns in accordance with an embodiment of the present invention;

FIG. 2 a is a scanning electron microscope (SEM) image of a fracturesurface of an Al₂O₃—TiC—Ti hollow yarn manufactured by the method inaccordance with the embodiment at a low magnification;

FIG. 2 b is a SEM image of the fracture surface of the Al₂O₃—TiC—Tihollow yarn manufactured by the method in accordance with the embodimentat a high magnification;

FIG. 3 a is a SEM image of a fracture surface of a TiC—Ni hollow yarnmanufactured by the method in accordance with the embodiment at a lowmagnification, with the fracture surface processed to form a mirrorsurface;

FIG. 3 b is a SEM image of the fracture surface of the TiC—Ni hollowyarn manufactured by the method in accordance with the embodiment at ahigh magnification, with the fracture surface processed to form a mirrorsurface;

FIG. 4 a is a SEM image of a fracture surface of a TiB₂ hollow yarnmanufactured by the method in accordance with the embodiment at a lowmagnification; and

FIG. 4 b is a SEM image of the fracture surface of the TiB₂ hollow yarnmanufactured by the method in accordance with the embodiment at a highmagnification.

DETAILED DESCRIPTION OF EMBODIMENTS

The above and other aspects, features and advantages of the inventionwill become apparent with reference to the following embodiments inconjunction with the accompanying drawings. Here, it should be notedthat the invention is not limited to the following embodiments and maybe realized in many different forms. Further, the following embodimentsare given by way of illustration to provide a thorough understanding ofthe invention to a person having ordinary knowledge in the art, to whichthe invention pertains. The scope and spirit of the invention is limitedonly by the claims and equivalents thereof. Like elements will bedenoted by like reference numerals throughout the specification anddrawings.

Embodiments of the present invention will now be described in detailwith reference to the accompanying drawings.

Method Using High Temperature Sintering

Conventionally, inorganic hollow yarns are manufactured using variousmethods.

In one method, a polymer and inorganic particles are sufficientlydispersed in an organic solvent, and are then spun through a spinneretto produce polymer-inorganic hollow yarns, which in turn are subjectedto heat treatment and sintering to form final inorganic hollow yarns. Inthis method, the inorganic particles are subjected to sintering, andsintering additives may be added for effective sintering. Examples ofthe inorganic hollow yarns produced by this method may include Al₂O₃hollow yarns, ZrO₂ hollow yarns, Ni hollow yarns, Ni—Fe hollow yarns,Perovskite hollow yarns, Si₃N₄ hollow yarns, and the like.

In another method, carbon and a Si—C polymer precursor are spun througha spinneret to produce hollow yarns, which in turn are subjected to heattreatment in a specific gas atmosphere. Examples of the inorganic hollowyarns produced by this method may include SiC hollow yarns, Si₃N₄ hollowyarns, carbon hollow yarns, and the like.

In both methods described above, it is necessary to perform heattreatment at high temperature, which results in large energyconsumption, and pore structures of the hollow yarns are determined byinorganic particles, particle growth and densification of reactantsduring the heat treatment.

Method Using Low Temperature Sintering

Most inorganic hollow yarns are oxide hollow yarns, such as Al₂O₃ hollowyarns. These Al₂O₃ hollow yarns need sintering at low temperatures toaccomplish a high level of porosity of 30˜50%, which is a preconditionfor use as an inorganic membrane supporter. However, if the sintering isperformed at low temperatures, the hollow yarns loose strength due tolow density and are likely to be broken during subsequent processes,such as membrane modulation, reproduction, and the like.

Method for High Strength and High Porosity Inorganic Yarns Needed

Accordingly, there is a need for a technique capable of manufacturinginorganic hollow yarns having high strength and high porosity. Examplesof such inorganic hollow yarns include cermet hollow yarns, which areceramic-metal composite hollow yarns, oxide-non oxide composite hollowyarns, poorly sinterable non-oxide hollow yarns, etc.

Some Other Methods

Now discussed are certain methods of manufacturing inorganic hollowyarns. In a first exemplary method, a polymer and oxide particles, forexample, NiO and Fe₂O₃, are dispersed in an organic solvent, followed bywet spinning and solvent exchange to produce polymer/NiO andpolymer/NiO—Fe₂O₃ hollow yarns, which in turn are sintered in areduction atmosphere, thereby forming Ni, Ni—Fe hollow yarns forhydrogen separation. Here the Ni, Ni—Fe hollow yarns have a completelydense structure.

In a second exemplary method, a carbon hollow yarn membrane is producedby thermal decomposition of a cellulose precursor. Then, carbon hollowyarns are produced by spinning and carbonizing a phenol resin, pitch,polyimide, poly acrylonitrile (PAN), and the like using the same method.Here, the carbon hollow yarns have a fine micropore structure.

In a third exemplary method, a polymer and Al₂O₃ particles as oxideparticles are dispersed in an organic solvent, followed by wet spinningand solvent exchange to produce polymer/Al₂O₃ hollow yarns, which inturn are subjected to heat treatment, thereby forming fine porous Al₂O₃hollow yarns.

In a fourth exemplary method, SiC, Si₃N₄-based hollow yarns are producedby melt spinning an organic silazane polymer, infusibilizing the yarnsto form an infusible layer on the surface of the yarns, and thermaldecomposition of the yarns. The infusibilizing process includesprocessing the hollow yarns in a gas containing Si, B, P, and metalcompound vapors and further processing the hollow yarns in a gascontaining water or ammonia. The hollow yarns prepared by this methodmay be effectively sintered to produce porous silicon-based hollowyarns.

In a fifth exemplary method, a thermoplastic polymer is mixed with Si₃N₄and Al₂O₃ particles, followed by melt spinning to preparepolymer-ceramic hollow yarns, which in turn are sintered to form Si₃N₄hollow yarns. Further, in this method, a thermosetting polymer andceramic particles are mixed with water and compressed to formpolymer-ceramic hollow yarns, which in turn are sintered to form ceramichollow yarns.

Composition for Inorganic Hollow Yarns

A composition for inorganic hollow yarns according to an embodimentincludes a self-propagating high temperature reactant, a polymer, adispersant, and an organic solvent.

Self-Propagating High Temperature Reactant

The self-propagating high temperature reactant is a raw material capableof inducing self-propagating high temperature reaction. When a localreaction of the self-propagating high temperature reactant is initiatedby heat treatment at a relatively low temperature, the self-propagatinghigh temperature reaction spontaneously occurs using the heat generatedfrom the initial reaction, which is a strong exothermic reaction. Withthe heat from the exothermic reaction, the temperature reaches severalthousand degrees Celsius, which far exceeds the temperature of the heattreatment.

The self-propagating high temperature reactant may form cermets, such asAl₂O₃/Fe, Al₂O₃/Ni, 4C/Fe, and TiC/Ni; poorly sinterable non-oxides,such as TiC, TiB₂, SiC, and Si₃N₄; oxide-non oxide composites, such asAl₂O₃/SiC, Al₂O₃/TiC, and the like, through self-propagating hightemperature reaction.

For example, when preparing Al₂O₃—TiC—Ti hollow yarns through theself-propagating high temperature reaction, 3TiO₂-4Al-1.5C may beprovided as a self-propagating high temperature reactant. In addition,when preparing TiC—Ni hollow yarns through the self-propagating hightemperature reaction, Ti—C—Ni may be provided as a self-propagating hightemperature reactant. Further, when preparing TiB2 hollow yarns throughthe self-propagating high temperature reaction, Ti-2B may be provided asa self-propagating high temperature reactant.

Although a fine reactant powder exhibits good properties when used inthe self-propagating high temperature reactant, too fine a reactantpowder can be oxidized to stop the self-propagating high temperaturereaction during wet spinning and drying. It is desirable to set the sizeof the reactant powder depending on the self-propagating hightemperature reactant.

The composition may contain the self-propagating high temperaturereactant in an amount of 45˜60 wt %. In order to ensure self-propagatinghigh temperature reaction, it is preferable that the self-propagatinghigh temperature reactant is contained at least about 45 wt % in thecomposition. On the other hand, to maintain moderate viscosity of thecomposition, which is needed for wet spinning, it is preferable that theself-propagating high temperature reactant is contained about 60 wt % orless in the composition.

Polymer

The polymer serves to maintain the shape of the inorganic hollow yarnand determines the microstructure of the inorganic hollow yarn. Examplesof the polymer include polysulfone, polyethersulfone,polyacrylronitrile, cellulose acetate, polyvinylidene fluoride,polyimide, and the like. These polymers may be used alone or in acombination of two or more thereof.

The composition may include the polymer in an amount of 6˜17 wt %.Efficient performance of the wet spinning is needed to maintain theshape of the hollow yarn. It is preferable to include about 6 wt % ofpolymer to accomplish such a degree of wet spinning. On the other hand,it is preferable to include the polymer about 17 wt % or less to avoidexcessive increase of the viscosity, which may make it difficult toachieve efficient wet spinning.

Dispersant

The dispersant serves to promote dispersion of the self-propagating hightemperature reactant while controlling the viscosity of the compositionduring preparation of the composition. Any suitable dispersant may beselected depending on the kinds of organic solvent and polymer. Whenpolysulfone is used as the polymer and N-methyl-2 pyrrolidone (NMP) isused as the organic solvent in the composition, polyvinylpyrrolidone(PVP), polyethyleneglycol (PEG) and the like may be selected as thedispersant. In some embodiments, the dispersant includes two or more ofpolyvinylpyrrolidone (PVP), polyethyleneglycol (PEG) and theirequivalents that are known in the art.

The composition may include the dispersant in an amount of 0.1˜4 wt %.It is preferable to include the dispersant is at least about 0.1 wt % inorder to accomplish generally uniform wet spinning as theself-propagating high temperature reactant powders have relatively lowdispersion. On the other hand, it is preferable to include thedispersant about 4 wt % or less to maintain the viscosity of thecomposition at a level for efficient wet spinning.

Organic Solvent

The organic solvent serves to peptize the polymer and dispersant whileacting as a dispersant medium for the self-propagating high temperaturereactant. Any suitable organic solvent may be selected depending on thekind of polymer. Examples of the organic solvent may includedimethylformamide, N-methyl-2-pyrrolidone, dimethylamide,dimethylacetamide, dimethyl sulfoxide, 1,4-dioxane, ethylene glycolmonomethyl ether, ethylene glycol monoethyl ether, diethylene glycoldimethyl ether, diethylene glycol diethyl ether, diethylene glycoldibutyl ether, and the like. These solvents may be used alone or in acombination of two or more thereof.

Diluent

In some embodiments, the composition may further include a diluent suchas oxide, nitride, carbide, metal, and the like. The diluent enablescontrol of a self-propagating high temperature reaction speed and amicrostructure of the inorganic hollow yarn by adjusting adiabatictemperature of the self-propagating high temperature reaction.

The diluent may be added up to an amount of 50 parts by weight withrespect to 100 parts by weight of self-propagating high temperaturereactant. If the amount of diluent exceeds 50 parts by weight, theself-propagating high temperature reaction may not occur.

Method of Manufacturing Inorganic Hollow Yarns

FIG. 1 is a flowchart of a method of manufacturing inorganic hollowyarns in accordance with an embodiment of the present invention.

Referring to FIG. 1, the method of manufacturing inorganic hollow yarnsincludes preparing a composition in S110, wet spinning in S120, washingand drying in S130, and inducing self-propagating high temperaturereaction in S140.

In S110, the composition is prepared by dispersing a self-propagatinghigh temperature reactant, polymer, and dispersant in the organicsolvent. In some embodiments, the composition contains 45˜60% wt % ofthe self-propagating high temperature reactant, 6˜17 wt % of thepolymer, 0.1˜4 wt % of the dispersant, and the balance of the organicsolvent.

In one embodiment, the composition is dispersed using a wet-type ballmill. In another embodiment, a rod mill can be used.

In one embodiment, the composition may be prepared in the form of aslurry by dispersing the self-propagating high temperature reactant,polymer, and dispersant in the organic solvent. Then, the slurrycomposition may be subjected to a ball-mill process, which may becarried out using a ceramic ball mill at 100˜400 rpm for 4˜168 hours,although not limited thereto. The prepared composition slurry may besubjected to degasification at 30˜80° C. for 4˜24 hours, although notlimited thereto, in a vacuum or a negative pressure environment.

Although not limited thereto and depending upon particular conditions,if the rotating speed of the ball mill is less than 100 rpm, ceramicballs may not easily move from a lower end of the ball mill to an upperend thereof. On the other hand, although not limited thereto anddepending upon particular conditions, if the rotating speed of the ballmill exceeds 400 rpm, the ceramic balls may rotate together with theslurry, causing insufficient dispersion of the composition slurry.

Further, the degasification removes bubbles staying in the compositionslurry and reduce the possibility of bursting of hollow yarns during wetspinning.

Next, in S120, the composition slurry is subjected to wet spinning, forexample, using a triple-spinneret. Here, three diameters determininginner and outer orifices of the spinneret are set in consideration ofinner and outer diameters of desired inorganic hollow yarns. Thecomposition slurry is introduced into the outer orifice of thetriple-spinneret by a gear pump, which may be operated at 5˜18 rpm,although not limited thereto. Further, water may be introduced at anintroduction speed of 8˜20 ml/min at a pressure of 1˜6 MPa into theinner orifice of the triple-spinneret by an LC pump.

Next, the slurry of hollow yarns spun through the triple spinneret isdropped into a washing bath containing with water. A distance between aninlet of the triple spinneret and a surface of the water may be 100 cmor less. The organic solvent in the slurry of the spun hollow yarns isexchanged with the water introduced into the inner orifice of the triplespinneret and filling the washing bath, so that polymer-self propagatinghigh temperature reactant hollow yarns are formed.

Here, the polymer-self propagating high temperature reactant hollowyarns may be wound around a spinning wheel after passing through aseparate washing bath. Further, the polymer-self propagating hightemperature reactant hollow yarns wound around the spinning wheel may besubjected to another washing process. The separate washing process ofthe polymer-self propagating high temperature reactant hollow yarnswound around the spinning wheel may be performed at 30˜100°C. for 6˜168hours, although not limited thereto. Finally, in S130, the polymer-selfpropagating high temperature reactant hollow yarns may be dried at80˜120° C. for 12˜48 hours, although not limited thereto, to remove thewater that has been provided by solvent exchange, which result inpolymer-inorganic hollow yarns.

Since the wet spinning in S120 and the washing and drying in S130 arewell known processes in the art in manufacture of the inorganic hollowyarns, any well-known methods may be adopted to perform theseoperations.

Next, in S140, the polymer-inorganic hollow yarns resulting from S130 issubjected to heat treatment, which removes polymer components remainingtherein and induces self-propagating high temperature reaction to formself-propagating high temperature products, such as cermets, poorlysinterable non-oxides, and oxide-non oxide composites, thereby producingfinal inorganic hollow yarns. In one embodiment, the heat treatment is asingle step heat treatment. In other embodiments, the heat treatmentincludes two or more heat treatment steps at different conditions suchas temperatures, time and/or different conditions.

Here, heat treatment for the self-propagating high temperature reactionis performed in air, nitrogen, helium, argon or hydrogen atmosphere. Toform a nitride, the heat treatment is advantageously performed in anitrogen atmosphere. On the other hand, to form a cermet comprising ametallic component, heat treatment is advantageously carried out innitrogen, helium, argon or hydrogen atmosphere. And, to form anoxide-carbide composite, heat treatment is advantageously carried out inair, nitrogen, helium, or argon atmosphere. In other words, one or twocomponents of the self-propagating high temperature reactant may besupplied in the form of gas during the self-propagating high temperaturereaction in S140 as well as in the preparation of the composition inS110.

The heat treatment in S140 initiates a reaction of the self-propagatinghigh temperature reactant. The reaction is a strong exothermic one andgenerates high heat, which can reach several thousand degrees Celsius.This high temperature further triggers spontaneous, continuing reactionsof the self-propagating high temperature reactant.

In embodiments, the heat treatment for the self-propagating hightemperature reaction is performed at a temperature greater than or equalto an ignition temperature of the self-propagating high temperaturereactant. The heat treatment triggers or induces the self-propagatinghigh temperature reaction, which in turn fuels additional reactions ofthe self-propagating high temperature reactant. Although the temperaturefor heat treatment depends on the self-propagating high temperaturereactant, the heat treatment of the self-propagating high temperaturereaction may be performed at 1000˜1800° C.

EXAMPLES

Next, the present invention will be described in more detail withreference to examples. Here, it should be understood that these examplesare provided for the purpose of illustration only and are not intendedto limit the scope of the invention in any sense.

A description of details apparent to a person having ordinary knowledgein the art will be omitted herein for clarity.

Example 1

TiO₂ powder having an average particle size of 0.2 μm, aluminum powderhaving an average particle size of #325, and colloidal graphite powderhaving an average particle size of 0.2 μm were dispersed in a molarratio of 3:4:1.5 in acetone by a wet-type ball-mill, followed by dryingat 60° C. for 24 hours in a vacuum, thereby preparing a 1000 g batch of3TiO₂-4Al-1.5C self-propagating high temperature reactant.

700 g of the self-propagating high temperature reactant, 100 gpolysulfone, 30 g PVP, and 400 g N-methyl-2-pyrrolidone were added to2000 ml polypropylene (PP), followed by dispersion using 400 g ofzirconia (ZrO₂) balls at 150 rpm for 48 hours at room temperature toprepare a slurry composition. The slurry composition was degassed at 50°C. for 12 hours in a vacuum to prepare a slurry composition for wetspinning.

The prepared slurry composition was passed through a triple spinnerethaving diameters of 1.4-0.8-0.55 mm and was then dropped into a waterbath for solvent exchange. The slurry composition was introduced at apressure of 3 atm. into an outer orifice of the triple spinneret and aninflow speed of the slurry composition was adjusted using a gear pump,which was operated at 12 rpm. Further, water was introduced into aninner orifice of the triple spinneret at an inflow speed of 14 ml/minand a pressure of 5 MPa by an LC pump. The washing bath was filled withwater at room temperature. A distance between an inlet of the triplespinneret and a water surface of the washing bath was 15 cm. Then,prepared polysulfone-3TiO₂-4Al-1.5C hollow yarns were washed with waterfor 48 hours at room temperature, followed by drying at 24 hours in avacuum, thereby providing final polysulfone-3TiO₂-4Al-1.5C hollow yarns.

The final polysulfone-3TiO₂-4Al-1.5C hollow yarns were subjected toprimary heat treatment at 800° C. for 4 hours to remove the polysulfonefrom the hollow yarns, and then subjected to secondary heat treatment at1500° C. for 4 hours to induce self-propagating high temperaturereaction (3TiO₂+4Al+1.5C=2Al₂O₃+1.5TiC-1.5Ti), thereby producingAl₂O₃—TiC—Ti inorganic composite hollow yarns. During the heattreatment, a temperature elevating rate was 4° C./min and a cooling ratewas 4° C./min.

FIGS. 2 a and 2 b are SEM images of a fracture surface of theAl₂O₃—TiC—Ti hollow yarn at a low magnification and a highmagnification, respectively. It can be seen that the producedAl₂O₃—TiC—Ti hollow yarn is a porous material, in which pores arethree-dimensionally connected to one another and have a size of severaldozen micrometers.

Example 2

Ti powder having an average particle size of #325, colloidal graphitepowder having an average particle size of 0.2 μm and Ni powder having anaverage particle size of #325 were dispersed in a molar ratio of 1:1:1by a dry-type vibration mill to prepare a 1000 g batch of Ti—C—Niself-propagating high temperature reactant.

Polysulfone-Ti—C—Ni hollow yarns were prepared by the same process asthe process of Example 1. The prepared polysulfone-Ti—C—Ni hollow yarnswere subjected to primary heat treatment at 800° C. for 4 hours toremove the polysulfone from the hollow yarns, and then subjected tosecondary heat treatment at 1500° C. for 4 hours to induceself-propagating high temperature reaction (Ti+C+Ni═TiC+Ni), therebyforming TiC—Ni inorganic composite hollow yarns. During the heattreatment, a temperature elevating rate was 4° C./min and a cooling ratewas 4° C./min.

FIGS. 3 a and 3 b are SEM images of a fracture surface of the TiC—Nihollow yarn at a low magnification and a high magnification, with thefracture surface processed to form a mirror surface. It can be seen thatthe produced TiC—Ni hollow yarn is a porous material, in which pores arethree-dimensionally connected to one another and have a size of severaldozen micrometers.

Example 3

Ti powder having an average particle size of #325 and boron (B) powderhaving an average particle size of #325 were dispersed in a molar ratioof 1:2 by a dry-type vibration mill to prepare a 100 g batch of Ti-2Bself-propagating high temperature reactant.

Polysulfone-Ti-2B hollow yarns were prepared by the same process as theprocess of Example 1 with the batch size reduced to 1/10 that ofExample 1. The prepared polysulfone-Ti-2B hollow yarns were subjected toprimary heat treatment at 800° C. for 4 hours to remove the polysulfonefrom the hollow yarns, and then subjected to secondary heat treatment at1500° C. for 4 hours to induce self-propagating high temperaturereaction (Ti+2B=TiB₂), thereby forming TiB₂ inorganic composite hollowyarns. During the heat treatment, a temperature elevating rate was 4°C./min and a cooling rate was 4° C./min.

FIGS. 4 a and 4 b are SEM images of a fracture surface of the TiB₂hollow yarn at low and high magnifications, respectively. It can be seenthat the prepared TiB₂ hollow yarn is a porous material, in which poresare three-dimensionally connected to one another and have a size ofseveral dozen micrometers.

As such, according to various embodiments of the present invention,since the inorganic hollow yarns are formed by the self-propagating hightemperature reaction which spontaneously proceeds using heat resultingfrom an initial strong exothermic reaction, the temperature of theself-propagating high temperature reactant reaches several thousanddegrees Celsius, exceeding the temperature for heat treatment by thereaction heat, thereby enabling manufacture of the inorganic hollowyarns, which cannot be obtained through general heat treatment.

Namely, targets of the inorganic hollow yarns are mainly limited tooxides when produced by conventional sintering, whereas the method ofthe present invention may expand the targets of the inorganic hollowyarns to cermets, poorly sinterable non-oxides and oxide-non oxidecomposites.

According to the embodiment, the inorganic hollow yarn manufacturingmethod employs self-propagating high temperature reaction, therebyallowing more easy manufacture of poorly sinterable hollow yarns.Further, since the self-propagating high temperature reactionspontaneously occurs by allowing an initial local reaction to occur atrelatively low temperatures, the method may achieve low energyconsumption.

Further, the inorganic hollow yarns produced by the method of theembodiment have a porous structure suitable for filters or membranes, inwhich pores are spontaneously and three-dimensionally connected to oneanother by a density difference between reactants and products beforeand after the self-propagating high temperature reaction, and by anon-filled volume of the reactant.

Further, when a bundle of polymer-self propagating high temperaturereactant hollow yarns is formed and then subjected to self-propagatinghigh temperature reaction, the hollow yarns may be easily formed into astructure wherein the yarns are strongly connected to one another byhigh temperatures up to several thousand degrees Celsius.

Further, the poorly sinterable ceramic hollow yarns and cermet hollowyarns produced by the method according to the embodiment exhibitsuperior thermal, mechanical, and chemical properties, thereby providingstability in fabrication and reproduction of membrane modules. Further,since the poorly sinterable ceramic hollow yarns and cermet hollow yarnsproduced by the method according to the embodiment contain metal, thepoorly sinterable ceramic hollow yarns and cermet hollow yarns exhibitgood chemical affinity to metal and thus permit easy production ofmembrane modules, which are used at high temperatures.

Moreover, according to the embodiment, the inorganic hollow yarns have alow thermal expansion coefficient, so that an intermediate layer orseparation layer may be prevented from being broken by thermal impactwhen formed of the inorganic hollow yarns, thereby improving reliabilityin fabrication of inorganic membranes.

Although some embodiments have been provided to illustrate the presentinvention in conjunction with the drawings, it will be apparent to aperson having ordinary knowledge in the art that the embodiments aregiven by way of illustration only, and that various modifications andchanges can be made without departing from the spirit and scope of theinvention. The scope of the invention should be limited only by theaccompanying claims.

1. A composition for inorganic hollow yarns comprising: 45˜60 wt % of aself-propagating high temperature reactant; 6˜17 wt % of a polymer;0.1˜4 wt % of a dispersant; and the balance of an organic solvent. 2.The composition of claim 1, wherein the self-propagating hightemperature reactant is a material capable of forming one of aceramic-metal composite, an oxide-non oxide composite, and a poorlysinterable non-oxide.
 3. The composition of claim 1, wherein the polymeris selected from polysulfone, polyethersulfone, polyacrylronitrile,cellulose acetate, polyvinylidene fluoride, and polyimide.
 4. Thecomposition of claim 1, wherein the organic solvent is selected fromdimethylformamide, N-methyl-2-pyrrolidone, dimethylamide,dimethylacetamide, dimethyl sulfoxide, 1,4-dioxane, ethylene glycolmonomethyl ether, ethylene glycol monoethyl ether, diethylene glycoldimethyl ether, diethylene glycol diethyl ether, and diethylene glycoldibutyl ether.
 5. The composition of claim 1, further comprising: adiluent selected from oxide, nitride, carbide, and metal, the diluentbeing added in an amount of 50 parts by weight with respect to 100 partsby weight of the self-propagating high temperature reactant.
 6. A methodof manufacturing inorganic hollow yarns, comprising: providing acomposition comprising a self-propagating high temperature reactant, apolymer, and a dispersant; wet-spinning the composition through aspinneret to form wet-spun yarns; washing and drying the wet-spun yarnsto form polymer-self propagating high temperature reactant hollow yarns;and heat-treating the polymer-self propagating high temperature reactanthollow yarns to remove a polymeric component from the polymer-selfpropagating high temperature reactant hollow yarns while inducingself-propagating high temperature reaction of the self-propagating hightemperature reactant to form inorganic hollow yarns.
 7. The method ofclaim 6, wherein the heat treatment of the polymer-self propagating hightemperature reactant hollow yarns is performed at an initial temperaturereaching 1000˜1800° C. for an initial reaction of the polymer-selfpropagating high temperature reactant hollow yarns.
 8. The method ofclaim 6, wherein the heat treatment of the polymer-self propagating hightemperature reactant hollow yarns is performed in air, nitrogen, argon,helium or hydrogen atmosphere.
 9. The method of claim 6, wherein thecomposition comprises 45˜60 wt % of the self-propagating hightemperature reactant; 6˜17 wt % of the polymer; 0.1˜4 wt % of thedispersant; and the balance of an organic solvent.
 10. The method ofclaim 6, wherein a reaction product of the self propagating hightemperature reactant is one of a ceramic-metal composite, an oxide-nonoxide composite, and a poorly sinterable non-oxide.
 11. An inorganichollow yarn manufactured by the method of claim 6.